The overarching goal of the proposed work is to more effectively incorporate patients' perspectives into the assessment of disease activity and burden among patients with ANCA-associated vasculitis [AAV, granulomatosis with polyangiitis (Wegener's), microscopic polyangiitis, and Churg-Strauss syndrome]. This project seeks to demonstrate the validity and feasibility of incorporating the Patient Reported Outcomes Measurement System (PROMIS) into clinical research in AAV. This project has five specific aims: Specific Aim 1: Determine the construct validity of PROMIS instruments in AAV through cross-sectional analysis of subjects within the Vasculitis Clinical Research Consortium (VCRC) patient cohort, utilizing other HRQOL instruments and physician-determined measures of vasculitis disease activity and damage as constructs. Specific Aim 2: Determine the longitudinal validity, responsiveness, and clinically important difference for the PROMIS instruments in an AAV population by comparing changes over time to the clinical evaluation, fatigue SF-36, and a patient global impression of change measure. Specific Aim 3: Determine the additive/complementary value of PROMIS assessments in defining the disease beyond standard measures of HRQOL and disease activity in AAV. Specific Aim 4: Use selected PROMIS instruments in a randomized therapeutic clinical trial in AAV. Specific Aim 5: Establish a tool box of PROMIS symptomatic measures that are the most useful for clinical research in AAV by assessing i) patients' ratings of the importance of the instrument domains; ii) the usefulness in describing the extent of the disease process; and iii) the relative efficiency and feasibility of the use of various PROMIS instruments in an RCT; and then providing researchers with informed guidance to integrate PROMIS into clinical investigation of AAV. The study will be conducted by the Vasculitis Clinical Research Consortium (VCRC), the largest collaborative clinical research infrastructure in North America and is fully responsive to the NIH RFA for PROMIS by utilizing already-established research cohorts and resources, including i) the VCRC Longitudinal Study cohorts for AAV; ii) the RITAZAREM clinical trial in AAV; and iii) the on-line VCRC Patient Contact Registry.